Recruitment software giant Bullhorn is today announcing a new owner: it’s been acquired by Vista Equity Partners in what TechCrunch understands is a deal the lower end of hundreds of millions of dollars. It is a fantastic return on investment in the company. Bullhorn, which was founded in 1999 in Boston, had raised $27.5 million to date from investors including Highland Capital, General Catalyst, GE Asset Management, Elmrock, Austin Investment Management and Charter Ventures, and in its last funding round in 2008 was valued at just $40 million.

Bullhorn has been profitable for the last year, TechCrunch understands. It had been talking to several other parties for a sale. In the last year it grew revenues by 40 percent while overseeing a billion transactions each month on its recruitment platform totalling $100 billion in client revenues. Boston Business Journal reports that its revenues were $33.6 million in 2011.

The company, which powers and manages recruiting and staffing operations for a range of businesses, from start-ups up to the world’s largest employment brands like Kelly, offers a range of services including mobile and social recruiting, as well as other SaaS services and consulting. It also occasionally releases interesting research on the job market and how recruitment is faring on the web. Bullhorn says it handles 150,000 job orders and placements each month, with more than 100,000 staffing and recruiting professionals across 126 countries using Bullhorn. It will continue to operate as a standalone company and will continue to expand its product offerings and geographic expansion.

Vista is known as an SaaS specialist, so Bullhorn will be a good fit for its existing portfolio. Other holdings include Accruent (performance software for real estate, education, corporate and wireless sectors); Big Machines (on-demand software solutions); Essential Learning and MicroEdge, among several others in a porfolio totalling $6.6 billion in committed capital. Bullhorn will continue to operate as a standalone company.

Bob Davis, a partner at Highland, tells TechCrunch that Bullhorn’s strength has been in its management team, led by CEO Art Papas, and its execution, especially over the last few years when the recruitment market has been hit hard by the economic downturn.

“It’s an exceptional management team and we were fortunate to have them thorugh one of the most difficult periods of time for recruitment and business,” he said. “We invested prior to 2008, and to keep the company intact — and to grow it during the last few years — is astounding. As a VC, finding a team to do that is exciting.”

Most of the current management team is expected to stay on post-acquisition, he said.

While this in itself is a pretty huge acquisition for the SaaS (and online recruitment) space — there may be another trend to point out here, too. It’s worth watching to see if private equity becomes a slightly bigger exit route for other companies now past the point of raising funds but either not yet ready to hit the public markets — or not wanting to given the current state of IPO markets and fright post Facebook, but still looking for more funds to continue their growth. Davis notes that Bullhorn is probably two years away from an IPO — a timeframe confirmed by its CEO Papas as well in the Boston Business Journal story.